mod_lock
mod/lock
Merge branch 'master' of https://github.com/coreos/etcd into mod-lock

Conflicts:
	mod/mod.go
Initial mod_lock acquire.
refactor(Node) do not expose node struct
refactor event
refactor change node_repr to node_extern
Lock testing.
Merge branch 'master' of https://github.com/coreos/etcd into mod-lock
teach store.Store about CompareAndDelete
track CompareAndDelete stats
add compareAndDelete event action
add the CompareAndDelete command
support CreateAndDelete through the v2 server
fix(README): repair some noisy spaces
keep the Delete tests together
implement recursive for CompareAndDelete in the store
update the v2 server to support recursive on CompareAndDelete events
feat(README): add a prevExist example

On the mailing list Dustin Oprea suggested adding a prevExist concrete
example would make it more clear that the value must be true or false.
fix tests bump deps